Well, at one point we were not alone. Other hominin species once walked the earth at the same time as Homo sapiens, including: Neanderthals, Denisovans, Homo luzonensis, Homo floresiensis, Homo erectus, Homo naledi, and others.

In fact, Neanderthals were still living in Europe until about 35,000 years ago, and Homo floresiensis lived in Flores island until about 50,000 years ago. So where did they all go? Studies suggest that some species died out because of climate change and environmental pressure.

Other studies suggest that it was actually us, Homo sapiens, that drove some human species to extinction, by outcompeting Neanderthals for food, for example. We had an advantage other human species didn’t have: the ability to cooperate in large numbers based on shared fictions. So when we encountered other Homo species, we had the upper hand. But it may not be that other human species went extinct, as much as merge into our gene pool as a result of assimilation and inter-breeding.

On top of the extinct Homo species we already know of, other species may soon be added to the list as scientists track down the identities of “ghost” populations of humans whose traces still lurk in our own genome.

So when you look at all the different human populations across the globe, remember that even if we may not look the exact same, we all belong to the same species, the only one that survived from the genus Homo: Homo sapiens. As corny as it might sound, we are indeed all one.